Conveyor systems

ABSTRACT

In a power-and-free conveyor system wherein carriers running in a carrier track system are propelled along the carrier track system by pushers depending from endless chains supported by a chain track system, a vertically displaceable platform is installed at a transfer region where the carriers are transferable from a main carrier track to a branch carrier track. The platform serves to lift a vertically displaceable rearward driving dog of a carrier into a position in which the dog is engageable by pushers on the chain of the main carrier track to advance the carrier along the branch carrier track.

D United States Patent 1 1 1111 3,882,787 Turner May 13, 1975 [54] CONVEYOR SYSTEMS 3,742,861 7/1973 Wilkinson 104/172 S 3,744,432 7 1973 P t 1. 4 [75] Inventor: John Turner, Argyle Works, me e a lo S Stevenage f f Primary Examiner-James B. Marbert Asslgneei Klng Llmlted Assistant Examiner-Robert Saifer [22] Filed: Mar. 13, 1973 21 Appl. No.2 340,836 [57] ABSTRACT In a power-and-free conveyor system wherein carriers running in a carrier track system are propelled along [30] Forelgn Apphc auon Pl-mmy Data the carrier track system by pushers depending from Nov. 26, 1972 United Kingdom 53050/72 endless chains supported by a chain track system a vertically displaceable platform is installed at a trans- [52] U.S. Cl 104/96; 104/172 S fer region where the carriers are transferable from a [51] hr. Cl. B65g 17/42 i carrier track to a branch carrier track The plab [58] Fleld of Search 104/96, 172 S f serves to i a Vertically displaceable rearward driving dog of a carrier into a position in which the 1 References cued dog is engageable by pushers on the chain of the main UNITED STATES PAT carrier track to advance the carrier along the branch 2,971,474 2/1961 Klamp 104/172 S rrier tra k- 2,987,012 6/1961 104/172 s 3,618,532 11 /1971 Clewett et al. 104/172 s 9 C 6 Dl'awmg Figures 3,623,538 11/1971 Wakabayashi et a1 104/172 S PATENTEB MAY 1 3 I975 SHEET 2 OF 5 PATENTEDHAY 1 31975 3,882,787

SHEEI u or 5 FIGS.

1 CONVEYOR SYSTEMS BACKGROUND OF THE INVENTION along the carrier track system by pushers depending from endless chains supported by a chain track system. Each carrier is equipped with a main driving dog, a holdback dog, and a supplementary driving dog. The main driving dog is movable between a raised position in which it is engageable by the pushers and -a lowered position in which it is not so engageable. The holdback dog and the supplementary driving dog are turnable between respective operati ve positions in which they are engageable by the pushers and respective inoperative positions in which they are not so engageable. The holdback dog is normally operative, while the supplementary driving dog is normally inoperative. At a transfer region where the carriers are transferrable from a faster-moving forwarding chain to a slower-moving receiving chain, there are mounted on the carrier tracks two cams, one of which serves to displace the holdback dogs of transferring carriers into their inoperative positions and the other of which serves to displace the supplementary driving dogs of the transferring carriers into the operative positions. For co-operation with the cams, each dog is provided with a follower in the form of a lateral projection from the dog.

At a transfer region where the carriers are transferable from a main carrier track to a branch carrier track, this known cam-and-follower arrangement has the disadvantage that the supplementary driving dogs are displaced by their associated cams at every transfer region, with resultant noise and wear,- irrespective of whether or not their carriers are to be transferred atthe region in question. Another disadvantage is that 7 changes in the layout of the cams can be a lengthy op eration involving re-design of the cams.

SUMMARY OF THE INVENTION According to the present invention, there is provided a conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an endless propelling chain supported by said chain track, pushers on the propelling chain arranged to push the carriers along the main path, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and

associated carrier is to be transferred, whereby noise and wear are relatively reduced.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 shows a sectional side elevation of part of a transfer region of a conveyor system with a platform in a lowered position,

FIG. 2 is a view similar to FIG. 1, but with the platform in a raised position,

FIG. 3 is a fragmentary sectional end elevation of that part from the direction of the arrow A in FIG. 2,

FIG. 4 shows a diagrammatic plan view of the transfer region,

FIG. 5 shows a diagrammatic plan view of the transfer region in a modified embodiment, and

' FIG. 6 shows a side elevation of part of the modified embodiment, with a platform in a raised position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 4, the conveyor system is an overhead power-and-free conveyor including a main carrier track M and branch carrier tracks (of which one is shown and referenced B) along which carriers travel. Each carrier consists of a forward trolley (not shown), a rearward trolley 2, and a yoke (not shown) interconnecting the two trolleys. Each carrier track consists of channels 3 in which the trolleys run. Extending at .a constant height above the carrier tracks are a number of power tracks (of which one is shown and referenced P) having the respective endless propelling chains carrying pushers 4. A main endless chain and a branch endless chain are indicated by the dash-dot lines CM and CB, respectively, in FIG. 4. The pushers 4 normally engage with forward driving dogs (not shown) on the forward trolleys to displace the carriersalong the carrier track system except for regions where the carriers are transferred in turn from one propelling chain to another propelling chain, for example a region where the carriers are transferred from a fast-moving chain to a slow-moving chain or a region as shown in FIG. 4 where the branch track B leaves the main track M. At these transfer regions, the pusher members 4 disengage from the forward driving dogs and engage respective supplementary, rearward driving dogs 6 on the trolleys 2, while the forward driving dogs are moved into the path of movement of the pusher members on the other propelling chain. When outside these regions, the rearward driving dogs 6 are normally kept by their own weight out of the path of movement of the pusher members 4 of each propelling chain.

FIGS. 1 to 4 show a means for displacing the dogs 6 into the path of the pusher member 4 at one of the transfer regions. The dog 6 is guided for vertical movement in the trolley 2 by two horizontal transverse pins 7 and the side plates 10 of the trolley 2 and the dog 6 carries at its upper end lateral projections 19 fixed thereto and projecting on both sides thereof. At the approach to the transfer region, the support track has mounted at the outside of one of its channels 3 a platform 20. The platfonn 20 has fixed thereto downwardly projecting pins 21 which are guided in bushes 22 for vertical movement relative to the support track.

The bushes 22 are fixed to the adjacent channel 3. The platform 20 is displaceable between a lowered, or' inactive position shown in FIG. I and a raised, or active position shown in FIG. 2. The platform is driven from its lowered to its raised position by a power drive in the form of a pneumatic piston-and-cylinder device 23 fixed to the adjacent channel 3. The piston rod 24 of this device 23 is connected via a link 25 to a parallelogram linkage 26. The linkage 26 comprises two parallel levers 27 having respective free ends to which are fixed respective rollers 28 which rotate about horizontal axes and which move in horizontal slots 29 in a vertical flange of the platform 20. The levers 27 have their pivots fixed to the channel 3. The top flange of the relevant channel 3 is cut away to receive the horizontal part of the platform 20 so that, when the platform 20 is in its lowered position shown in FIG. 1, the uppermost surface of the platform 20 is flush with the uppermost surface of the top flange of the channel 3.

In operation, as a load carrier approaches a transfer region, the leading trolley (not shown) of the load carrier operates a limit switch to energize a solenoid valve which opens to allow compressed air into the device 23. Where the transfer region is one from the main carrier track M to a branch track B, this limit switch 32 is mounted on the branch track B and is operated by the leading trolley as the latter begins to take the branch track B under the guidance of the switch plate 31. The solenoid valve is referenced 33 in FIG. 4. The piston rod 24 is moved outwards and, through the linkage 26, raises the platform 20 from the position shown in FIG. 1 to the position shown in FIG. 2. The platform 20 is so positioned with respect to the transfer region-that, when the leading trolley of the load carrier is at the transfer location, the rearward trolley 2 is at the location of the platform 20. As the platform 20 rises, it lifts the dog 6 into a position in which the dog is engageable by a pusher 4. If necessary, the dog 6 may be maintained in its raised position after it has left the platform 20 by a fixed horizontal support 34 shown in FIG. 2. The pusher 4 pushes the load carrier until the leading trolley is picked up by the receiving power chain. Thereupon, the solenoid 33 is de-energized and the device 23 lowers the platform 20.

In an alternative embodiment illustrated in FIGS. and 6, the parts 23, 32 and 33 are replaced by a lever system 35, and the leading trolley 36 acts directly on a lever 37 of this system to turn the levers 27 to raise the platform 20. To effect lowering of the platform 20, the left-hand lever 27 nearer the branch track B is extended downwards as at 38 so that when the platform is in its raised position shown in FIG. 6 the lever projects into the path of movement of a ramp 30 of the rearward trolley 2, so that the ramp 30 hits the extension 38 and thus lowers the platform 20.

Advantageously, the pushers 4 are of such a width that the pushers on the chain CM will push the leading trolley sufficiently far forward at the transfer region for the pushers of the chain CB to engage the forward driving dog, thus eliminating any need for an auxiliary transfer unit.

A particular advantage of the embodiments described is that, at a transfer region where a branch track leaves the main track, the platform is lifted only when a load carrier is to be transferred to the branch track. This minimizes noise and wear. An additional advantage is that the position of the platform along the track can be adjusted without great difficulty, so that the transfer arrangements are relatively flexible.

What is claimed is:

l. A conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an

endless propelling chain supported by said chain track,

pushers on the propelling chain arranged to push the carriers along the main path, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and a dog-operating member movable to displace the dogs between their operative positions and their inoperative positions, and means which is actuated by a carrier in said transfer region when a leading portion of the carrier takes said branch path, but not by a carrier in said region continuing on said main path, to move said dog-operating member from an initial position to displace the dog on the carrier between its operative position and its inoperative position, and which is actuated by the carrier when a trailing portion of the carrier leaves said main path to return said dogoperating member to said initial position.

2. A conveyor system according to claim 1, wherein said pushers depend from said chain and said dogs are displaceable upwardly from their inoperative positions into the path of movement of said pushers, and wherein said dog-operating member comprises a platform and said actuatable means serves to lift said platform when a carrier in said transfer region takes said branch path, but not when a carrier in said transfer region continues on said main path.

3. A conveyor system according to claim 2, further comprising guide means for guiding movement of said platform so that said platform is lifted and lowered perpendicularly to said path of movement of said pushers.

4. A conveyor system according to claim 1, wherein said means actuated by said carrier comprises a fluidoperated piston-and-cylinder device, and control means located at said branch path and actuatable to actuate said piston-and-cylinder device for actuation by a carrier in said transfer region taking said branch path.

5. A conveyor system according to claim 4, wherein said control means comprises a limit switch and a solenoid valve actuatable by said limit switch.

6. A conveyor system according to claim 1, wherein said dog is a supplementary driving dog.

7. A conveyor system according to claim 1 wherein said means actuated by a carrier comprises an actuator element positioned in the path of travel of a carrier in said branch path for effecting movement of said dogoperating member when a carrier takes said branch path.

8. A conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an endless propelling chain supported by said chain track, pushers depending from the propelling chain arranged to push the carriers along the main path, said dog beingdisplaceable upwardly from their inoperative positions into the path of movement of said pushers, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and a dog-operating platform movable to displace the dogs between their operative positions and their inoperative positions, means actuatable by a carrier in said transfer region taking said branch path, but not by a carrier in said region continuing on said main path, to lift said platform to displace the dog on the carrier between its operative position and its inoperative position, and guide means guiding movement of said platform so that said platform is lifted and lowered perpendicularly to said path of movement of said pushers, said actuatable means comprising a parallelogram linkage including first and second parallel levers turnable about respective substantially horizontal axes, and first and second substantially horizontal slots in said platform in which act upper end zones of the respective levers.

9. A conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an endless propelling chain supported by said chain track,

pushers on the propelling chain arranged to push the carriers along the main path, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and a dog-operating member movable to displace the dogs between their operative positions and their inoperative positions, and means actuatable by a carrier in said transfer region taking said branch path,

. but not by a carrier in said region continuing on said the carrier. 

1. A conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an endless propelling chain supported by said chain track, pushers on the propelling chain arranged to push the carriers along the main path, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and a dog-operating memb movable to displace the dogs between their operative positions and their inoperative positions, and meAns which is actuated by a carrier in said transfer region when a leading portion of the carrier takes said branch path, but not by a carrier in said region continuing on said main path, to move said dog-operating member from an initial position to displace the dog on the carrier between its operative position and its inoperative position, and which is actuated by the carrier when a trailing portion of the carrier leaves said main path to return said dogoperating member to said initial position.
 2. A conveyor system according to claim 1, wherein said pushers depend from said chain and said dogs are displaceable upwardly from their inoperative positions into the path of movement of said pushers, and wherein said dog-operating member comprises a platform and said actuatable means serves to lift said platform when a carrier in said transfer region takes said branch path, but not when a carrier in said transfer region continues on said main path.
 3. A conveyor system according to claim 2, further comprising guide means for guiding movement of said platform so that said platform is lifted and lowered perpendicularly to said path of movement of said pushers.
 4. A conveyor system according to claim 1, wherein said means actuated by said carrier comprises a fluid-operated piston-and-cylinder device, and control means located at said branch path and actuatable to actuate said piston-and-cylinder device for actuation by a carrier in said transfer region taking said branch path.
 5. A conveyor system according to claim 4, wherein said control means comprises a limit switch and a solenoid valve actuatable by said limit switch.
 6. A conveyor system according to claim 1, wherein said dog is a supplementary driving dog.
 7. A conveyor system according to claim 1 wherein said means actuated by a carrier comprises an actuator element positioned in the path of travel of a carrier in said branch path for effecting movement of said dog-operating member when a carrier takes said branch path.
 8. A conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an endless propelling chain supported by said chain track, pushers depending from the propelling chain arranged to push the carriers along the main path, said dog being displaceable upwardly from their inoperative positions into the path of movement of said pushers, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and a dog-operating platform movable to displace the dogs between their operative positions and their inoperative positions, means actuatable by a carrier in said transfer region taking said branch path, but not by a carrier in said region continuing on said main path, to lift said platform to displace the dog on the carrier between its operative position and its inoperative position, and guide means guiding movement of said platform so that said platform is lifted and lowered perpendicularly to said path of movement of said pushers, said actuatable means comprising a parallelogram linkage including first and second parallel levers turnable about respective substantially horizontal axes, and first and second substantially horizontal slots in said platform in which act upper end zones of the respective levers.
 9. A conveyor system, comprising carriers, a main path along which the carriers travel, a branch path which branches from the main path at a transfer region and along which the carriers travel, a chain track extending along said main path at a spacing therefrom, an endless propelling chain supported by said chain track, pushers on the propelling chain arranged to push the carriers along the main path, a dog on each carrier displaceable between an operative position in and an inoperative position out of the path of movement of the pushers, and a dog-operating member movable to displace the dogs between their operative positions and their inoperative positions, and means actuatable by a carrier in said transfer region taking said branch path, but not by a carrier in said region continuing on said main path, to move said dog-operating member to displace the dog on the carrier between its operative position and its inoperative position, and said actuatable means comprising a lever system which includes a part located at said branch path for actuation by a carrier in said region taking said branch path and another part located at said main path for actuation by a carrier at said region taking said branch path to return said dog-operating member to its initial position following actuation of the first-mentioned part of said lever system by the carrier. 